Occurrence of multidrug resistance associated with extended-spectrum β‑lactamase and the biofilm forming ability of Escherichia coli in environmental swine husbandry

Extended-spectrum beta-lactamase (ESBL) production and biofilm formation are mechanisms employed by Escherichia coli to resist beta-lactam antibiotics. Thus, we aimed to examine antibiotic resistance associated with ESBL production and biofilm formation in E. coli isolates from swine farms in Southern Thailand. In total, 159 E. coli isolates were obtained, with 44 isolates identified as ESBL producers, originating from feces (18.87 %) and wastewater (8.80 %) samples. All ESBL-producing strains exhibited resistance to ampicillin (100 %), followed by the cephalosporin group (97.73 %) and tetracycline (84.09 %). Multidrug resistance was observed in 17 isolates (38.63 %). Among the isolates from feces samples, the bla_GES gene was the most prevalent, detected in 90 % of the samples, followed by bla_CTX-M9 (86.67 %) and bla_CTX-M1 (66.67 %), respectively. In the bacteria isolated from wastewater, both bla_GES and bla_CTX-M9 genes were the predominant resistance genes, detected in 100 % of the isolates, followed by bla_CTX-M1 (64.29 %) and bla_TEM (50 %), respectively. Strong biofilm formation was observed in 11 isolates (36.67 %) from feces and 4 isolates (25.57 %) from wastewater samples. Notably, nearly 100 % of ESBL-producing strains isolated from feces tested positive for both pgaA and pgaC genes, which play a role in intracellular adhesion and biofilm production. These findings contribute to the understanding and potential control of ESBL-producing E. coli, and the dissemination of antibiotic resistance and biofilm-related genes in swine farms.